Drip irrigation methods are known as one of plant cultivating methods. In the drip irrigation methods, a drip irrigation tube is disposed on the soil, and irrigation liquid such as water and liquid fertilizer is slowly supplied from the drip irrigation tube into the soil on which plants are planted, for example. The drip irrigation methods can minimize the liquid consumption, and therefore have increasingly attracted attention in recent years.
Such a drip irrigation tube typically has a tube and a dripper. Typically, the dripper supplies the irrigation liquid in the tube space to the soil at a set rate at which the irrigation liquid drips into the soil. Known examples of the dripper include a dripper which is disposed in such a manner as to stick into a tube from outside, and a dripper which is bonded on an inner wall of a tube.
The latter dripper has, for example, a channel including a pressure reduction channel that allows liquid, which has flowed from the tube space to the dripper, to flow toward a through hole of the tube while depressurizing the liquid; and a diaphragm that changes the volume of a part where the depressurized irrigation liquid flows in accordance with the liquid pressure in the tube space. The dripper is composed of three members, i.e., a member bonded to the inner wall of the tube, a member disposed on the member bonded to the inner wall of the tube, and the diaphragm disposed between the two members. The diaphragm is formed of an elastic film such as a silicone rubber film (see, e.g., PTL 1).
The drippers can suppress variations in the ejection amount of the irrigation liquid regardless of changes in liquid pressure in the tube space. Therefore, the dripper is advantageous from the perspective of growing multiple plants uniformly.